Proposal of interaction length for stimulated Brillouin scattering threshold of nanosecond laser in optical fiber

●A concept of interaction length is proposed to analysis SBS threshold of nanosecond laser in optical fiber.●An equation is proposed for the first time to depict interaction length.●The relationship of SBS threshold and interaction length is demonstrated.●The validity of the concept is verified by detailed experiments.

A concept of interaction length is proposed. Interaction length, which is dependent on pulse width, repetition rate and fiber length could be used to model and analyze the stimulated Brillouin scattering threshold (SBST) of nanosecond laser in optical fiber. The relationship of SBST of nanosecond fiber laser and interaction length was demonstrated. The validity of the concept is verified by detailed experiments.